|Feature : Power|
|Used for describe power lines and associated infrastructure.|
The power=* tag is used to identify a wide range of facilities and features that relate to the generation and distribution of electrical power including power lines, power generation, pylons and sub-stations. WikiProject Power networks gives more details of the project to map electricity distribution.
Very useful for navigation.
The number of wires in each cable can tagged using wires=single, wires=double or wires=quad. All towers also have one or more earth wires strung from the top.
National Grid call the things "towers" as they're free-standing, but common usage seems to be "pylon"
In England and Wales, higher-voltage (>= 275kV) lines are operated by National Grid. Lower voltage lines are operated by distribution network operators (UK Power Networks, Western Power Distribution, etc) with regional scope. Different DNOs have different construction standards, so while the transmission network is consistent across the country, the distribution network has substantial design variations.
In the UK, each National Grid power line appears to have a two character identifier and each tower along that line appears to be numbered. For example ZM is the West Weybridge to Chessington line, and each tower is numbered ZM 1, ZM 2, etc. I propose that these be recorded, if known, for each tower with the ref tag. For example: power=tower, ref=ZM 35. Higher-voltage DNO lines use similar schemes, sometimes with three-letter line identifiers (e.g. PTC connects Burwell to Fulbourn Grid).
In the UK there is a hierarchy of power lines that is easy to identify. Most are identifiable over long distances which makes them useful for navigation. Other countries follow very similar schemes (not surprising as the design is constrained by the same physics and economics). Starting at the low-voltage end, we have:
- Wooden poles carrying four wires on small ceramic insulators, or bundles of insulated cables twisted together. These lines are usually 400 V between phases, which directly provide the domestic 230 V supply. Most of these follow roads and paths.
- Wooden poles with two or three widely-spaced bare wires on large insulators having one or two plates. These lines are 11,000 volts - often used for distribution in rural areas.
- Wooden poles with three bare wires on multi-plate insulators are 33,000 V or 45,000 V between phases - usually on higher and more substantial poles, sometimes poles are used in pairs and sometimes two circuits are run in parallel on the same poles.
- Metal towers carrying a set of single wires (usually three plus an earth wire on top) are 132,000 V. These are gradually disappearing.
- Towers with three or six double wires are 275,000 V
- Towers with three or six quadruple wires are 400,000 V
The number of conductors (i.e. single, double, triple) is simply relevant to the current handling capacity, and not more or less likely to be seen for any particular voltage. Similarly, the number of 3-phase circuits (groups of 3 cables) is simply a matter of capacity required, since single-circuit paths are (somewhat surprisingly) much cheaper to construct - the cost of the cables themselves apparently being the most significant factor.
In Japan, see User:Nahainec/PowerLine.
A mapCSS stylesheet is available for josm.